A 47-year-old female was thrown from a car when it went down a bank near Waipukurau yesterday.
Senior Sergeant Dan Foley said police were called to the crash in Ashley Clinton at 12.45pm.
The car had gone down the bank near the bridge that runs over the Tukituki River.
The serious crash unit was called to the scene and a number of police attended.
The woman was "slipping in and out of consciousness" and was airlifted to hospital by the Lowe Corporation rescue helicopter, he said.